OSLO, Norway -- The anti-Muslim extremist who confessed to a bombing and youth camp massacre that killed 77 people in Norway has told investigators he also considered attacking other targets linked to the government or the prime minister's Labor Party, police said Saturday.

During a 10-hour questioning session on Friday, Anders Behring Breivik asked interrogators how many people he had killed in the July 22 attacks, and "showed no emotion" when they told him, police attorney Paal-Fredrik Hjort Kraby told reporters in Oslo.

The 32-year-old Norwegian has confessed to setting off a car bomb that killed eight people in downtown Oslo and then gunning down scores of youth from the left-leaning Labor Party at their annual retreat on an island northwest of the capital. Sixy-nine of them died.

Kraby said Breivik had considered other possible targets to strike as he prepared what Norway's Police Security Service has described as a meticulously prepared attack by a lone culprit.

"The other targets were government and Labor Party targets," Kraby said.

He declined to confirm a report in Norwegian tabloid VG saying Breivik had described the Royal Palace and the Labor Party's head office as potential targets. The paper did not cite its sources.

"They were targets that one would say are natural for terror attacks," Kraby told reporters.

Breivik released a 1,500-page manifesto before the attacks in which he ranted against Muslims and a left-wing political elite he claims is destroying Europe's cultural heritage by allowing unfettered immigration.

Norwegian authorities say he wasn't in their database of right-wing extremists and appears to have prepared his attacks for years, without telling anyone, even his friends and family. They haven't found anything to support his claims of being part of a militant network of modern-day crusaders plotting a series of coups d'etat across Europe.

Norway started burying the dead Friday, and Cabinet ministers honored the victims in tearful memorial services in churches and mosques. Prime Minister Jens Stoltenberg has called for unity across ethnic and religious lines to face Norway's greatest peacetime tragedy.

On Saturday, national broadcaster NRK and the Norwegian Radio Orchestra hosted a memorial concert in the Oslo Cathedral to honor the victims and the rescuers who helped panicked survivors escape the massacre on Utoya island.

The once-homogenous country has become increasingly diverse in recent decades. More than 12 percent of the 5 million residents are immigrants or children of immigrants. About half of the immigrants come from Asia, Africa or Latin America, according to the national statistics office.

Worries about immigration have fueled the rise of the Progress Party, a right-wing opposition group that is now the No. 2 party in Parliament, after Labor. Party officials have confirmed that Breivik used to be a member. In his manifesto, he says he left the group because he thought they were too moderate.

Progress Party leader Siv Jensen said after the attacks that she was "embarrassed and disgusted" to find out that Breivik was a former member of the party.